In software defined networks (SDNs), data plane processing, which includes the physical forwarding of data from sources to destinations, is decoupled from control plane processing, which includes making decisions concerning which routes in the SDN are to be used to forward the data from the sources to the destinations. Due to this decoupling, it is expected that routing decisions for at least some future SDNs will be made by a centralized network controller residing in the cloud. It is further expected that such a centralized network controller will have access to real time data concerning the topology and state of the SDN, and will receive requests to provide routes (e.g., end-to-end data path connections) for network traffic flows. Such requests may include flow routing requests for rerouting of flows due to traffic surges and/or failure events, as well as occasional new routing requests (e.g. between data centers), possibly for limited durations of time.
Wherever possible, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts, elements, etc.